lu Pratt, Polydicuta froui the Falkland Islands. 



The parapodia of the 28th segment of G. congoensis, 

 and G. Juipfcri correspond with the median parapodia 

 (about lOOth segment) in the species from the Falkland 

 Islands and Norway, in that the notopodium is a well 

 developed structure. 



The lower limb of the notopodium of this species differs 

 markedly from that of the tropical G. congocnsts, in that in 

 the latter the notopodium bears no capillary bristles, their 

 place being taken by two fairly stout acicula which just 

 appear above the surface. This form is like another tropical 

 form, ? G. longicirrata, in the presence of multi-acicula and 

 the absence of capillar)' bristles in the notopodium. 



In the Falkland Islands specimen the lower limb of 

 the notopodium does not appear until the 56th segment, 

 when it has the form of a small finger-shaped process, 

 devoid of bristles, which, however, as previously stated, 

 are present on the succeeding segments. In a specimen 

 of G. norvegica which I have examined, the lower limb of 

 the notopodium appears on the 35th segment. 



Throughout the Polychaeta, a typical parapodium 

 consists of a notopodium and a neuropodium, each bearing, 

 in addition to the ordinary bristles, a single aciculum. 

 The extra-tropical species of GoTiiada have typical para- 

 podia, but in two tropical forms (one of which, owing to 

 the absence of characteristic features, Arwidsson doubt- 

 fully places in this genus) the parapodia are modified, in 

 that the notopodium is multi-aciculate and the ordinary 

 bristles are absent. Therefore we may assume that the 

 form of parapodium possessed b)- extra-tropical forms is 

 the primitive one, and that from it the modified form 

 seen in some tropical species has been derived ; that is 

 tosay,the parapodium of extra-tropical forms has remained 

 true, while that of tropical forms shows a tendency to 

 variation. 



